Colonic adenocarcinoma with osseous metaplasia in a horse.

The research paper discusses a case of colon adenocarcinoma with bone-like changes (osseous metaplasia) in an old mare that exhibited chronic weight loss and recurrent abdominal pain.

Case Description

• A 30-year-old mixed-breed mare presenting with chronic weight loss and intermittent abdominal pain was examined. The abdominal discomfort she experienced was refractory, meaning that it was persistent and did not respond well to common treatments.
• Upon rectal palpation, a mass was discovered in the right caudoventral region of her abdomen. This method allows veterinarians to assess the size, shape, and position of abdominal structures.

Hematologic and Serum Biochemical Findings

• The horse’s blood and serum tests mostly showed normal results. However, she displayed slight mature neutrophilia, indicating an increase in mature neutrophils, which are white blood cells that fight infection.
• She also had mildly elevated alkaline phosphatase activity and total bilirubin concentration. High levels of these substances in the blood could suggest liver disease or damage, or in the case of alkaline phosphatase, bone disease.

Cytological Examination

• The mare underwent an abdominocentesis, a procedure to collect a sample of fluid from the abdominal cavity. An equal number of non-degenerative neutrophils and macrophages were found, but no neoplastic (cancerous) cells were identified in the sample.

Euthanization and Necropsy

• Despite the efforts, the mare continued to show signs of abdominal discomfort. As a result of her deteriorating condition, the decision was made to euthanize the horse.
• A post-mortem examination (necropsy) was conducted, which revealed a large mass at the junction of the right dorsal colon and transverse colon, and several smaller masses in the liver.

Final Diagnosis

• The findings from the necropsy indicated the presence of a severe disease. The large mass in the colon was identified to have characteristics consistent with colonic adenocarcinoma with osseous metaplasia.
• Colonic adenocarcinoma refers to malignant (cancerous) tumors that arise from glandular structures in the colon’s inner lining. Osseous metaplasia is an unusual phenomenon where bone tissue is found in areas it is not typically present.